This invention relates to a plastic lens which can be tinted to affect contrast and vision characteristics in low light conditions. It has applicability to eye protecting devices such as goggles used in an outdoor or other adverse environment, a safety goggle, eyeglasses, masks, and visors.
Goggles which are intended for use in an outdoor or other adverse environment include sports goggles such as winter sports including skiing, snowboarding, snowmobiling, or motorcycle use, as well as safety goggles. Other eye protecting devices include eyeglasses, masks for helmets, and visors. Such eye protecting devices provide protection for the wearer""s eyes from external air and particulate matter. A goggle for outdoor use may have vent apertures open to external air flow to exchange air between the exterior environment and the interior of the goggle. Such a vented exchange of air will minimize fogging caused by moisture in the air condensing on the lens of the goggle. The vent apertures are typically covered by a porous foam to control the air exchange while forming a partial barrier to snow, dust and other particulate matter. Such goggles can also include replaceable plastic lenses which may be a single lens or a double lens, and such lenses can be tinted in various colors to assist in contrast and glare protection.
Certain improved contrast resolution capabilities have been available in fixed glass lenses for eyeglasses and sunglasses, such as eyewear having a green or other colored lens which assists in contrast resolution capabilities. Goggles having a removable plastic lens which is tinted in a manner to improve contrast resolution for a wide variety of light levels including sunlight are disclosed in our U.S. Pat. No. 6,138,286 issued Oct. 31, 2000 and entitled xe2x80x9cGoggle Having A Tinted Plastic Lensxe2x80x9d. The tint is adapted to the plastic materials usable in goggle lenses to provide improved visual performance and anti-fogging characteristics. In particular, the tint creates a transmission curve characterized by several peaks and valleys along the visible wavelength spectrum which conforms to certain characteristics of the human eye to improve contrast in a removable plastic lens useful in goggles for skiing and other outdoor sports.
While the eyewear described above provides improved contrast resolution capabilities for sunlight and certain low light conditions, there remains a need for improved performance in still lower light conditions including twilight and night use particularly when illuminated by artificial light sources. The types of known tinted lenses have less utility in very low light conditions such as night skiing on ski slopes which are artificially lighted.
A tinted lens for goggles and other eyewear is provided which overcomes certain of the problems and disadvantages of prior tinted lenses and goggles using such lenses. Eye protecting devices utilizing the tinted lenses disclosed herein have particular utility in low light conditions such as, for example, determining changes in level of surfaces of a snow covered slope which is artificially lighted to allow night skiing.
In particular, the invention includes a tinted plastic lens of specialized characteristics having a transmission curve of particular shape and transmission levels which improve contrast in low light conditions, including night conditions which are artificially illuminated. The invention has particular utility for a winter sports goggle for night use on artificially lighted slopes or low light day use, but is also adaptable to eyewear for motorcycle use, safety shields, visors, safety goggles and the like which are to be used in low light conditions.
A better understanding of the present invention along with other objects and advantages will become apparent from the following description and with reference to the following drawings.